The instant invention relates to the machine tool industry and, more particularly, to a coupling which is particularly adapted for use in a workholding system, and to a clamp for securing receiver and carrier portions of the coupling together in a coupled position.
Frequently during the manufacture of precision parts, such as parts for aircraft engines and the like, machining operations are carried out in a series of steps utilizing different machining apparatus at a series of different work stations. Further, in many cases, substantial quantities of identical parts are produced utilizing the same series of steps at the work stations. In order to achieve the necessary precision in machining operations of this type, each time a workpiece is transferred to a different work station, the workpiece must be precisely set up or installed and secured in a workholding apparatus at the station. Frequently, set-up operations of this type are very time consuming because of the high degree of precision which is required to properly orient and secure a workpiece for a machining operation. In fact, it has been found that frequently set-up operations of this type consume substantially greater quantities of time than the actual machining operations at the work stations. As a result, substantial quantities of operational time on highly expensive machining apparatus are frequently consumed by set-up and adjustment procedures, rather than actual machining operations.
The instant invention provides a novel coupling construction which is operable in a workholding system for substantially reducing the amount of time which is required for set-up and adjustment procedures at work stations before machining operations can be commenced. Specifically, the coupling construction of the instant invention comprises a carrier and a receiver which are receivable in a coupled position, and a clamp which is operable for securing the carrier and the receiver in the coupled position. The receiver and the carrier are preferably both of generally circular configuration, and they are preferably formed with multi-toothed coupling surfaces thereon which are of complementary configurations and which are receivable in interfitting face-to-face mating relation with each other. The carrier and the receiver are further formed with clamping surfaces thereon, which face in generally the opposite directions from the respective coupling surfaces thereof, and the clamp of the coupling is operative for engaging the clamping surfaces of the receiver and the carrier for releasably securing them in the coupled position. The coupling is preferably formed with a central open area, and preferably a plurality of the clamps are provided and disposed in a substantially circular array in the open area for releasably securing the carrier on the receiver. Further, the clamping surfaces of the carrier and the receiver which preferably face generally opposite to each other and substantially parallel to the coupling surfaces of the coupling are located so that they communicate with the central open area, and hence the clamps are preferably disposed entirely within the open area. In addition, preferably the clamping surfaces and the clamps are disposed and configured so that when clamping pressures are applied to the clamping surfaces, they are applied substantially along clamping axes which are substantially perpendicular to and intersect the coupling surfaces. As a result of these structural features, the entire coupling, comprising the carrier, the receiver, and the clamps, can be constructed in a reduced profile so that the coupling can be received in a machining apparatus without occupying a substantial portion of the machining envelope of the apparatus, i.e. the area of the apparatus where machining is performed. Further, since the clamping pressures are applied along axes which are substantially perpendicular to and intersect the coupling surfaces, the clamping pressures are, in effect, applied directly to the coupling surfaces to optimize the clamping effect.
The clamp of the instant invention which is adapted for use in securing the coupling in the coupled position preferably comprises a clamp body having a central axis, a clamping member which is attached to the body and extends generally outwardly therefrom, a slide member which is slidably received on the body so that it is slidable a distance with respect thereto in a direction which is substantially parallel to the axis of the body, spring means which is operable substantially along the axis of the body for biasing the clamping member toward the slide member, and actuating means which communicates with the slide member and with the spring means for moving the clamping member to a clamping position and for loading the spring means to bias the clamping member toward a clamping surface. More specifically, when the clamp is assembled in the coupling the actuating means communicates with the slide member and with the spring means for moving the clamping member from a position wherein it is inwardly offset from the clamping surface of the carrier to a position wherein it is substantially aligned with but disengaged from the clamping surface of the carrier. The actuating means is further operative for moving the clamp from the aligned but disengaged position thereof to a position wherein the clamping member is in engagement with the clamping surface of the carrier and for thereafter loading the spring means to bias the carrier towards the receiver. Further, the actuating means of the clamp is positionable in a locked position wherein substantial clamping pressures are maintained on the carrier and on the receiver until the clamp is manually moved to an unclamped position. The clamp is preferably received and secured in the receiver so that it is maintained in a position wherein it is in engagement with the clamping surface of the receiver, and wherein the clamping member of the clamp is engageable with the clamping surface of the carrier to clampingly secure the carrier to the receiver. Further, the clamp is preferably operable by manipulating a lever arm of the actuating means for moving the clamping member and for biasing it toward the carrier clamping surface. In the preferred embodiment of the clamp, the actuating means is operative for moving the clamp between the above described positions with a double toggle action, wherein the actuating means is pivotable about a first axis which is substantially transverse to the axis of the body for moving the clamping member from the inwardly offset position to the aligned disengaged position. After the clamping member has been moved to the aligned disengaged position, the actuating means of the clamp is pivotable about a second axis which is substantially transverse to the axis of the body for moving the clamping member into engagement with the carrier clamping surface and for thereafter loading the spring means of the clamp to apply clamping pressures to the clamping surfaces of the carrier and the receiver. The spring means of the clamp, which is operative for biasing the carrier and the receiver together, preferably comprises one or a plurality of Bellville washers which are compressed when the lever arm of the actuating means is pivoted to load the spring means. As a result of loading the Bellville washers with the actuating means, substantial pressures can be applied to the clamp to firmly secure the carrier and the receiver in biased engagement in the clamped position.
In the preferred embodiment of the coupling, wherein a plurality of clamps are provided for securing the carrier and the receiver in the clamping position, a drive means is provided which communicates with the lever arms of the individual clamps so that the clamps can be simultaneously actuated for movement between the various above-described positions thereof. As a result, unnecessary torques and stresses in the coupling can be avoided, and the carrier and the receiver can be quickly and efficiently clamped and unclamped as desired. Preferably, the drive means is located in the central open area in the receiver, and preferably, it is remotely operable either mechanically or hydraulically.
Accordingly, because of the operational and structural features of the coupling construction and the clamp of the instant invention as hereinabove set forth, the coupling can be effectively utilized to provide a reliable and accurate workholding system. The coupling can be effectively embodied in a low-profile construction, wherein the clamps are disposed in the interior of the coupling, and hence the coupling can be utilized in a workholding system without occupying a substantial portion of the working envelope of a machining apparatus. Therefore, the capabilities and capacities of a machining apparatus are not substantially limited when the coupling is utilized in combination therewith. For utilizing the coupling of the instant invention in a workholding system to carry out a procedure wherein a plurality of substantially identical workpieces are formed in a series operation and wherein each piece is machined at a series of different work stations, an assembly comprising a receiver and a plurality of the clamps is secured at each of the work stations, and each of the workpieces is attached to a different carrier. In order to perform the first machining operation at a work station, a carrier with a workpiece attached thereto is secured to the receiver at the work station and the usual set-up procedures are performed in order to properly orient and position the coupling and the workpiece at the work station before a machining operation can be commenced. However, after the machining apparatus at the work station has been set up to accommodate one workpiece on a coupling at the station, a second workpiece mounted on a second carrier can be substituted for the first workpiece and carrier and clamped to the receiver at the work station. Because of the highly accurate and reliable manner in which the carrier and the receiver are receivable in coupled relation, the set-up procedures which were required when the first workpiece was installed at the work station are unnecessary in subsequent workpiece installations at the same station. Therefore, after initial set-up operations have been completed at each work station, workpieces can be moved from work station to work station, and machining operations can be performed on the workpieces without substantial further set-up operations at the stations. As a result, substantial savings in time are realized in the overall machining operation, and workpieces can be produced at a substantially increased rate. Further, it has been found that the coupling of the instant invention can be effectively utilized in workholding systems for a variety of different machining apparatus, including milling machines and rotary machining apparatus, such as lathes and grinders. Hence, the coupling has substantial application in a variety of machining operations which can be performed in a wide variety of manufacturing industries.
Apparatus representing the closest prior art to the instant invention of which the applicant is aware is disclosed in the U.S. Pat. No. to PERRY 3,540,566. However, this apparatus is not adapted for a low-profile construction, and hence when it is utilized in a workholding system it occupies a substantial portion of a machining enelope. The apparatus disclosed in this patent also does not embody or suggest the operational and structural features of the coupling construction and clamp of the instant invention as hereinabove described, and hence this reference is believed to be of only general interest.
Accordingly, it is a primary object of the instant invention to provide a coupling construction which can be effectively adapted for use in a workholding system.
Another object of the instant invention is to provide an effective substantially circular coupling construction which can be embodied with a reduced axial dimension.
A still further object of the instant invention is to provide a clamp which can be effectively utilized in a coupling for a workholding system.
A still further object of the instant invention is to provide a means of reducing the set-up time for machining operations wherein a plurality of substantially identical workpieces are sequentially machined at a series of different work stations.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.